This invention relates to packaging machines, especially those of the type designed to apply and secure a web of material to containers, as well as to cutting mechanisms for severing the web of material between adjacent containers and to conveyors and container supports for such packaging machines.
It is well known to use a packaging machine to apply a continuous web of heat sealable film or other material to a series of containers supported on a conveyor. In all such machines, it is necessary to separate or sever the continuous web of material between adjacent containers after the web has been applied and secured to the container. Various types of severing or cutting devices have been used in the past with such machines with varying success.
One prior known type of cutter includes opposed cutting blades which are reciprocated toward and away from one another in order to shear the web of material at the desired location. Another type of cutter is that shown in U.S. Pat. No. 3,851,445 and includes a slitter which is reciprocated diagonally across a moving conveyor to cut the web of material. A third type of cutter is a continuously rotated cutter such as those shown in U.S. Pat. Nos. 3,436,894 or 3,706,183. With each of the above types of cutting or slitting assemblies, complex timing devices such as belts, chains, gears or extensive levers or the like were necessary to enable the appropriate shearing, slitting or severing action to take place properly between adjacent containers so as to avoid damage to either the container or the web material secured to the container.
A second problem encountered with the above type of packagers has been the inability or relative difficulty in modifying the packaging conveyor to support different sizes of containers. In the type of packager with which the present invention is concerned, open-topped, formed thermoplastic containers are slipped in apertures in generally horizontally extending plates secured in some fashion to a conveyor which carries them under a web applying and securing structure. As is apparent, various sizes and shapes of containers require different support plates having different sizes or shapes of receiving apertures. In prior packaging machines or conveyors, a change in container supports required substantial time and effort including either changing the conveyor support chains or other supporting devices, separate securement of different size plates with threaded fasteners and support brackets to the prior existing chains, or other time-consuming procedures. This, in itself, was a difficult and laborous operation which often necessitated a packaging concern to purchase two or three different packagers each with its own size container support plates in order to avoid the time consuming job of changing container supports.
The above changeover problems also resulted in problems with the cutting, shearing or slitting apparatuses for the continuous web material. In prior machines, if the container supports were changed or their locations modified to support different sizes of containers, adjustment and retiming of the cutting apparatus was also necessary. That is, either the chains, gears or levers which timed the shearing, slitting or continuously rotating cutting action of the prior known cutting assemblies had to be changed so that the cutting action occurred at the proper place and time with respect to the new container supports. This, too, added further time and labor expense to the conversion of the packager from one size container support to another.
In addition to the above problems, prior packaging machines utilized web-cutting assemblies which were often very complex and required frequent sharpening or normal maintenance even when the container supports were not changed. This resulted in frequent down time for the packager and additional expense for repairs.
The present invention was conceived in recognition of and as a solution for the above problems.